Display quality of an image is one of the indicators for judging the performance of a display device in the field of display technology; and the image display with high quality is always a desirable goal for the manufacturers. Currently, for a large-size display device, there is a problem that the brightness display is uneven. This uneven brightness display is mainly caused by both uneven electrical properties of thin film transistors (TFTs) in a back plate and uneven backlight provided by a backlight module arranged at the back of a liquid crystal display (LCD) panel.
The uneven backlight from a backlight source is mainly derived from the structural design of the backlight module. Currently, a typical backlight module includes a backlight source (e.g., an LED light stripe), a reflector, a light guide plate, a diffuser, and a prism film. Especially, two diffusers are required. The light from a point light source LED is reflected by the light guide plate, and thereby an area (surface) light source is formed. The light from the area light source is transmitted by the reflector below the light guide plate toward the diffuser, and then enters a display panel through the prism film.
Generally, the backlight module of an LCD panel includes a dozen of, or dozens of, Light Emitting Diodes (LEDs). The LEDs are packaged into a light stripe and then fixed at a side of the LCD module. In actual production, it is impossible to ensure the even brightness for respective regions of the entire LCD panel, so the backlight brightness is uneven. For example, for an image of a solid color, both bright and dark regions will occur, and thereby the image quality of the LCD panel will be affected adversely.
In the prior art, the machining precision and the quality of the backlight source may be improved so as to prevent the occurrence of uneven backlight brightness. However, in this way, it is impossible to obtain a desired effect, and meanwhile the cost of the LCD module will increase dramatically.